in general, components in blood for a human body are measured by using a clinical examination equipment or a biochemical analysis equipment. In a facilitated or simplified blood sugar (glucose) level (concentration) measuring equipment which is used for checking a clinical state of a diabetic, a blood sugar level is measured by coating blood collected needle-stickingly from an earlobe or a finger tip of the diabetic on a test paper including enzyme which is thereby change in light absorption degree representing the blood sugar level, as described in "Rinsho Byori, XXIX, 7, page 713, 1981" by Sachiko Kamei, et al., "BME, Vol. 1, No. 11, page 852, 1987" by Akiyuki Okubo, and "Saishin Kansa, Vol. 7, No. 1, 1989" by Hajime Taishi, et al.
A blood sugar level measuring equipment using amperometric biosensor has been proposed these days, as described in "The Lancet, April 4, page 778, 1987", "Kiso-to-Rinsho, Vol., 25 No. 9, page 2877, 1991" by Haruko Shirai, et al., and "Rinsho Kensa Kikie Shiyaku, Vol. 14, No. 3, page 409, 1991" by Hideaki Kurata, et al.
In the measuring equipment, an enzyme field effect transistor (ENFET) and an electrodes are so dipped in solution including sampled blood that a current flowing through the ENFET is changed in accordance with the enzyme reaction of glucose, as well described in the U.S. Pat. No. 4,909,921. Consequently, a blood sugar level can be measure from the change of the current value. The equipment comprises a main unit and a sensor unit, wherein the sensor unit is inserted into the main unit for the calibration of the sensor unit prior to the time of measuring a blood sugar level.
In the calibration of the sensor unit, calibration standard solution is dripped on the ENFET and the electrode, and a series of measuring steps are carried out. In a further calibration of the sensor unit, a correction chip corresponding to a lot number of a sensor included therein is so inserted into the main unit that the sensitivity of the equipment is corrected. In a still further calibration of the sensor unit, correction data is supplied to the main unit in accordance with bar-codes labelled thereon to correct the sensitivity of the equipment.
In the blood sugar level measuring equipment thus calibrated, a blood sugar level of a diabetic is measured, and the measured data is memorized and/or told or reported to a doctor or nurse by the diabetic.
In the conventional blood sugar level measuring equipment, however, there is a disadvantage in that the sensitivity of a sensor is deviated dependent on sensor fabricating conditions and a lot number of enzyme used therein, because the enzyme used therein is biological. Further, there is a disadvantage in that it is required to calibrate a sensor prior to the measurement of a blood sugar level, because the sensitivity of the sensor is lowered during the storage or usage thereof. This calibration is troublesome for the elderly and children. Still further, there is a disadvantage in that measured data is intentionally erased or changed in level by a diabetic, if the data is worse for and/or is not a level to be expected by the diabetic.